This K08 Award proposal is a three-years plan to develop the candidate into an independent investigator in the area developmental behavioral neurology and includes a study of the cortical and subcortical brain mechanisms that may underlie behaviors observed in children with Attention Deficit Hyperactivity Disorder (ADHD). This proposal provides for the candidate's development through formal course work, extensive mentorship in a collaborative research environment, and implementation of a study that is the first step towards a larger body of research aimed at understanding the neurobiological basis of ADHD, a complex, heterogeneous disorder that has been reported to have multiple etiologies and is in need of specification at the neurobiological level. Primary mentorship will be provided by Martha B. Denckla, M.D., Director of the candidate's department. Dr Denckla is a leading researcher in the field of developmental behavioral neurology who has extensive experience training young investigators. In addition, a panel of seven consultants, most of whom work in a collaborative environment with the candidate and mentor, will each provide training on a specialized area of expertise critical to the candidates development. Immediate career goals include acquiring knowledge and experience in the use of neurobehavioral paradigms and relatively new techniques (volumetric and functional Magnetic Resonance Imaging (MRI) as theses apply to the study of frontal-subcortical systems involved in the pathogenesis of ADHD. Long-term career goals are directed towards using these paradigms and techniques to investigate the role of aberrant brain mechanisms in the pathogenesis of developmental disorders such as ADHD, autism, Tourette's syndrome, and learning disabilities. The study will examine 40 children with ADHD ages 8 through 12 years, and 40 controls. Experimental neurobehavioral paradigms, morphometric MRI and functional MRI (fMRI) will be used to investigate the hypothesis that the syndrome of ADHD is related to dysfunction within an anterior frontal network, comprised of the frontal lobes and interconnected subcortical structures including the basal ganglia and cerebellum.